Telephone-exchange system.



H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 8. ms.

Mknasses: I I mve/r/or. 19%. e Henry f? Clause/7L Patented Jan. 2, 1917.

TA is HENRY P. CLAUSEN, OF 'MOUNT VERNON, NEW YORK, ASSIGNGR, BY'MESNE'ASSIGN- MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A. CORPORATION OF new YORK.

Specification of Letters Patent.

TELEPHONE-EXCHANGE SYSTEM.

Application filed September 8,,1915. SerialN'o. 49,476;

lowing is a full, clear, concise, and exact 'description.

, This invention relates to telephone exchange systems, and more particularly to such systems of the central energy type.

In telephone exchange systems now in use, considerable difliculty is experienced in handling calls for engaged subscribers lines.

Calling for a line and finding it engaged, a subscriber must call again. and it frequently happens that before reaching the desired line, a subscriber may call several times. This takes up the time of an operator and is of considerable annoyance to the subscriber.

It is an object of this invention to overcome these difiiculties, and to provide a telephone exchange system in which a subscriber calling another subscriber and finding the line engaged, may then ask the operator to call when the desired line is not engaged.

A link circuit is provided by means of which anoperator may plug into the jacks of the calling and called lines without telephonically connecting the two lines. The

talking strands of this link circuit are preferably normally open. With this link circuit associated with each line, both subscribers may I call for and be connected to other lines without in any way affecting the link circuit, but as soon as both lines become idle, apparatus in the link circuit functions to close the talking strands thereof and to furnish a signal to the operator. Preferably only a few link circuits of this character are furnished in each operators position, the interconnection of lines ordinarily being handled by means of regular link circuits.

For a more complete understanding of this invention, reference should be made to the accompanying drawing, wherein is illustrated a telephone exchange system showing one embodiment of the invention and comprising the usual subscribers stations A and B and a cord circuit C located at a central ofiice for interconnecting the subscribers. stations. For convenience, only two subscribers lines are shown in the drawing, but it is to be understood that many more such lines terminate at the central-office. Cord circuit D, shown in the drawing, is of the usual bridged-impedance, tworconductor-type, andv is ordinarily used in connecting two lines for conversation. It is intended that only a few cord circuits, similar to C, will be provided' at each operators position, while the majority of the cord circuits at an operators position will be similar to D.

Suppose that subscriber B is'connected by means of cord circuit D with another subscriber whose line terminates at the central oflice, and that subscriber A initiates a call, desiring to be connected with subscriber B; the operator, in: response to the line signal of subscriber A, answers by inserting the answering plug of a cord circuit similar to D. Finding that subscriber A desires to be connected with subscriber B, the operator, testing and finding Bs line busy, so advises A. A may then request that he be called when Bs line becomes idle and hang up his receiver, in which case the operator withdraws the answering plug of the cord circuit from the jack of As line, and connects plug of cord circuit C with a multiple jack of As line and plug 6 of this cord circuit with a multiple jack of Bs line.

The-insertion of plug 5, into a multiple jack of As line does not alter the condition of any apparatus associated with Asline or with that end of cord circuit C. The inser-' tion of plug 6 into a multiple jack of Bs line causes the operation of slow release relay 7, due to a flow of current from battery in a cord circuit D connected with another jack of Bs line. The operation of relay 7 causes the operation of slow release relay 8 over a circuit from battery, through contact 10 of relay 7 and right-hand winding of relay 8 to ground. Relays 7 and 8 remain in operated condition as long as the plug of cord circuit D is inserted in a jack of Bs line. As soon as this plug is removed, how ever, relay 7 releases, thereupon causing the operation of relays and 16. The energizing circuit of these two relays may be traced from battery, through contact 11 of relay 7, contact 17 of relay 8, the windings of relays 15 and 16 in parallel, contact 18 of relay 8 and contact 19 of relay 20 to ground. The operation of relays 15 and 16 closes the talking strands of cord circuit C, and causes the operation of relays 21 and 22 and the cut-off relay associated with lines A and Patented'J'an, 2; 1917.,

B. The operation of relay 21 causes the operation of relay 23 over an energizmg cir- CllltwfI'Oll'l battery,.through contact 25 of relay 8, winding of relay 23, and contact of relay 21 to ground. Relay 23 upon operating, completes a locking circuit for itself, which may be traced from battery, through contact 31 of listening key 32, contact 33 and winding-of relay 23, and contact 30 of relay 21 to ground. The operation of relays 21 and 22 completes a locking circuit for relays 15 and 16 from battery, through contact 11 of. relay 7 contact 34 of relay 22, the windings of relays 15 and 16 in parallel, contact 35 of relay 21, and contact 19 of relay 20 to ground. The operation of these relays 21 and 22 closes their respective contacts 36 and37 Relays 21, 22 and 23 being operated, close a circuit for supervisory lamps 40 and 41. Thiscircuit may be traced from battery, through lamps4Qand 41in parallel, contacts 36 and 37, of relays 21 and 22in parallel, contact '42 of relay 23, and interrupter 43 to ground. The completion of thisioircuit causes the supervisory lamps 40 and 41 to flash intermittently. This serves as 'a signal to the operator that both lines A andBare now not busy. The operator may now actuate listening key 32,.thereby opening the locking circuit of relay 23 which disconnects the interrupter from the circuit of lamps 40 and 41, and substitutes ground has back-contact 47 of relay 23 so that supervisory lamps 40 and 41 burn steadily. The operator. then actuates ringing keys 45 and 46 to sendringing current over lines A and B tosignal these two subscribers. V The subscrlbers, 1n responclmg to ther nging of their respective call bells, remove the receivers from the switchhooks, thereby caus ing the operation of relays 48 and 49fwhich open the circuits of supervisory lamps 4O and 41. After completing the conversation,

apparatus associated with As line-and with,

that end of -rcord circuit C was not altered. While cord circuit C was connected with the multiple jacks of lines A and B, and at the sainetime the .cord circuit D was connected with a jack of Bs line and a' jack of another line, subscriber A might initiate a call, desiring to be connected with another subscriber whose line terminates in a central office. The operator observing the line signal associated with As line, wouldinsert the'answering'plug' of a cord circuitsimilar to D into the answering jack of- As line and complete the connection to thewantedsubscribers line. The insertion of the answering plug of a cord circuit similar to D into the answering jack ofAs line, causes the energization of relay 20 of cord circuit C, completing a circuit through the left-hand winding of relay 8. If,

while the. subscriber ,A;was talking to, an-

other subscriber, the cord circuit D is disconnected from'thejack of 'Bs line, relay 7. would *release, but no circuit would be'completedfor relays 15 and 16 because;

contact 19 of relay 20 is open, When the answering plug of the cord circuit similar 'to D is removed from the answering jack of As line, relay20 releases thereupon com pleting a'circuit for relays .15 and 16. After the operation of these relays 15 and 16, the 1 other apparatus in the cord circuit C functions, as hereinbefore described, to complete the talkingstrandsof cord circuit C and to cause the flashing of supervisory signals 40 and 41, The operator may then signal subscribers A and B as hereinbefore.

It will be observed that the insertion of plugs 5' and .6 into the multiple jacks of lines A and B does not alter the electrical condition ofthe sleeve strands, of the a'cks' Consequently these lines are not made busy, due to cord circuit 0.. It will further: more be observed that by utilizing the telephone exchange system. embodying. applicants invention, awaiting subscriber; may call and be called without afiecting the waitingconnection in any manner whatever. Relays 7, 8' and, 20 have, hereinbefore been however, is considerably slower in releasing referred to as slow-release'relaysi Relay 8,.

than relays .7. and; 20. l This is necessary. in

order that relays 21, 22 and 23 may operate after the operation of relays 15 and 16 and before relay 8 releases. lCord circuit D is of the ordinary type and is believed'to require no description. It is to be understood that this cord circuit D will be provided with a listening and a ringing key, as is the usual practice; What is claimed is: i 1. In a telephone exchange system, subscribers lines terminating in a plurality of switching terminals .at a central office, a link circuit thereat having coiiperating switching terminals connecting two of said lines, asecond link circuit having switching terminals for connecting a thirdline and one of said connectedlines and adaptedto be connected therewith without altering the electrical condition of the switching terminals of said lines, a signaling device associated with the second link circuit, and apparatus associated with the second link circuit operating when the first link circuit is disconnected from said busy line to cause the operation of the signaling device.

2. In a telephone exchange system, subscribers lines terminating at a central office, a link circuit thereat connecting. two of said lines, a second link circuit for connecting a third line with either of said connected lines, said second link circuit having normally open talking strands, a signaling de vice for the second link circuit, apparatus associated with said second link circuit preventing the closure of the talking strands thereof when one end of the second link circuit is connected to a busy line, apparatus associated with the second link circuit operating to close the talking strands thereof when the busy line becomes idle, and means actuated upon the operation of the second mentioned apparatus for causing the operation of the signaling device.

3. In a telephone exchange system, subscribers lines terminating in a plurality of switching terminals at a central office, a link circuit having cooperating switching terminals connecting two of said lines, a second link circuit having switching terminals for connecting a third line and one of said connected lines and adapted to be connected therewith without altering the electrical condition of the switching terminals of said lines, a supervisory signaling device associated with each end of said second link circuit, and apparatus associated with said secondlink circuit operating when said first link circuit is disconnected from said busy line to cause the operation of said supervisory signaling devices.

4. In a telephone exchange system, subscribers lines terminating in a plurality of switching terminals at a central office, a link circuit having cooperating switching terminals connecting two of said lines, a second link circuit having switching terminals for connecting a third line and one of said connected lines and adapted to be connected therewith without altering the electrical condition of the switching terminals of said lines, a supervisory signaling device associated with each end of said second link circuit, a circuit-interrupting device, and apparatus associated with said second link circuit operating when said first link circuit is disconnected from said busy line to include said supervisory signaling devices and said circuit-interrupting device in circuit, whereby said signaling devices are caused to furnish intermittent signals to an operator.

5. In a telephone exchange system, subscribers lines terminating at a central office, a link circuit thereat for interconnecting said lines and adapted to be connected with two busy lines to establish a waiting connection therebetween, said link circuit having normally open talking strands, apparatus associated with said link circuit preventing the closure of the talking strands while said lines are busy, and apparatus operating when said busy lines become idle to close the talking strands.

6. In a telephone exchange system, subscribers lines terminating at a central oifice, a link circuit thereat interconnecting two of said lines, a second link circuit for interconnecting a third line and one of said connected lines, said second link circuit having normally open talking strands, two relays in said second link circuit operated upon the connection of said second link circuit with one of said connected lines, one of said relays releasing upon the disconnection of said first link circuit from the line connected with said second link circuit, a third relay operating upon the release of said last mentioned relay to close breaks in the talking strands of said second link circuit, a signaling device for the second link circuit, an operating circuit for the signaling device, and means actuated upon the operation of the third relay for closing the operating circuit.

7 In a telephone exchange system, subscribers lines terminating at a central office, a link circuit thereat interconnecting two of said lines, a second link circuit for interconnecting a third line and one of said connected lines, said second link circuit having normally open talking strands,two relays in said second link circuit operated upon the connection of said second link circuit with one of said connected lines, one of said relays releasing upon the disconnection of said first link circuit from the line connected with the second link circuit, a third relay operating upon the release of said last mentioned relay to close breaks in the talking strands of the second link circuit, a signaling device for the second link circuit, interrupter mechanism, and relay mechanism actuated upon the operation of the third relay for including the interrupter mechanism in circuit with the signaling device.

In witness whereof I hereunto subscribe my name this 7th day of September, A. D. 1915.

HENRY P. CLAUS'EN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

